1. Field of the Invention
The present invention relates to a display device, and for example, to a display device the display elements of which are constructed by self-emitting elements.
2. Description of the Related Art
With the spread of various information processing apparatuses, display devices come in various forms in accordance with their functions. Among them, so-called self-emitting type display devices in which display elements are constructed by self-emitting elements are gathering attention. In such display devices, a display device in which organic electro-luminescence (EL) elements or organic light-emitting diodes, for example, are used as the display elements thereof is known. Such a display device is directed to reduce power consumption since a backlight is not needed and has advantages such as high visibility of pixels and faster response compared to liquid-crystal displays of the related art. In addition, such a display device has properties similar to diodes, and thus, luminance thereof can be controlled by the amount of current flowing through the elements. Such a self-emitting display device is described, for example, in JP 2006-91709 A.
However, in the display device having such a configuration, the light-emitting elements thereof generally have such properties that the internal resistance of the elements changes with the use period and ambient atmosphere. Particularly, as the use period increases, the internal resistance will increase with time, and the amount of current flowing through the elements also decreases. Therefore, for example, when pixels at the same position in the screen are continuously lighted when displaying a menu window on the screen, a burn-in phenomenon occurs in that portion. In order to correct this state, it is necessary to detect the states of the pixels. In this detection method, the states of the pixels are detected in the display blanking period. In the blanking period, since pixels are not lighted, no voltage is applied. Therefore, by using an additional power source different from a power source used for lighting to apply a predetermined current to pixels during the blanking period and detect a voltage in the current-applied state, the burn-in-related deterioration is detected from a change in the voltage.
As a method of detecting and correcting the pixel state, as disclosed in JP 2006-91860 A, for example, a method is known in which monitoring elements are arranged in parallel in each row direction of the light-emitting elements of a display section, and a main current source supplies a constant current to the monitoring elements so that a voltage generated in the monitoring element is applied to plural light-emitting elements arranged in the row direction in parallel to the monitoring element, and the light-emitting elements are driven with a constant voltage.
JP 2003-174601 A discloses another method in which by driving a display region in accordance with time, a slope of a burn-in at the boundary between a video display portion and a mask portion is made dull, and a difference in the luminance and color of the video near the boundary is made inconspicuous when the video is displayed in full mode.
The display device disclosed in JP 2003-174601 A makes a difference in the luminance and color of the video near the boundary between the burned-in portion and a nonburned-in portion inconspicuous as described above and is able to relieve the burn-in itself but is unable to solve it. Moreover, when the burn-in phenomenon is corrected by detecting the pixel state and correcting the luminance deterioration between adjacent pixels, the tonality will be nonconstant and color balance will become improper if the burned pixels are simply corrected without discrimination.